1. Field of the Invention
The invention generally relates to Wireless Local Area Network (WLAN) authentication, and more particularly, to communication systems for integrating WLAN technology and cellular network technology, and WLAN authentication methods thereof.
2. Description of the Related Art
With rapid developments in ubiquitous computing and networking, various wireless technologies have been developed, such as the WLAN technologies, including Wireless Fidelity (WiFi) technology, and Bluetooth technology, etc., and the cellular network technologies (or called Wireless Wide Area Network (W-WAN) technologies), including Global System for Mobile communications (GSM) technology, General Packet Radio Service (GPRS) technology, Enhanced Data rates for Global Evolution (EDGE) technology, Wideband Code Division Multiple Access (WCDMA) technology, Code Division Multiple Access 2000 (CDMA-2000) technology, Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) technology, Worldwide Interoperability for Microwave Access (WiMAX) technology, Long Term Evolution (LTE) technology, and Time-Division LTE (TD-LTE) technology, etc.
Due to the fact that different wireless technologies have different characteristics, such as bandwidths, average coverage, service rates, and costs, etc., having a plurality of wireless modules integrated in a single communication device has become a popular choice for providing convenience and flexibility for users. However, integrated wireless modules generally operate independently. For example, a general mobile phone may support the WiFi technology and at least one cellular network technology, and more and more Wireless Access Points (WAPs) are capable of simultaneously providing the Hotspot service of the WLAN technology and the femto-cell function of at least one cellular network technology. Specifically, the communication protocol of the WiFi technology specifies operations, such as association, authentication, and transmission/reception, etc., and the communication protocol of the at least one cellular network technology specifies operations, such as connection establishment, and transmission/reception, etc., wherein the operations associated with the WiFi technology and the cellular network technology are performed independently. Thus, it is desirable to have a more flexible and efficient way of authentication for such integrated communication systems.